Body fat is a good measure of how healthy
a hummingbird is, and how well it is eating. A hummingbird's skin is
thinner than a plastic sandwich bag, and just as clear. Under the skin
fat is whitish yellow, which shows up easily against red muscles. Nancy
holds the hummimgbird upside down (there is more fat on the underside
than the back) and blows on the chest feathers. When the feathers part,
she can see the skin and how much fat is there.

Checking
Fat

Nancy uses a regular
drinking straw to gently blow on a hummingbird's underside.

Blowing makes the feathers
fly up, showing the skin and the muscles and fat.

It's tricky to blow
and look through a magnifying glass at the same time. Nancy's
had lots of practice.

Can you see little
whitish fat deposits under this hummingbird's skin?